Enzyme Activity and Inhibition Quiz

What effect does a high pH have on enzymes?

• Increases enzyme activity

• Causes denaturation

• Enhances substrate binding

• Stabilizes enzyme structure

Answer explanation

A high pH can disrupt the ionic and hydrogen bonds that maintain an enzyme's structure, leading to denaturation. This alters the enzyme's active site, reducing its activity and ability to bind substrates effectively.

What are enzyme inhibitors?

• Molecules that increase enzyme activity

• Molecules that decrease or halt enzyme activity

• Molecules that stabilize enzyme structure

• Molecules that enhance substrate binding

Answer explanation

Enzyme inhibitors are molecules that decrease or halt enzyme activity, preventing the enzyme from catalyzing reactions effectively. This distinguishes them from molecules that enhance or stabilize enzyme function.

What is a characteristic of competitive inhibitors?

• They bind to an alternative site on the enzyme

• They resemble the substrate and compete for the active site

• They increase the enzyme's Vmax

• They do not affect substrate concentration

Answer explanation

Competitive inhibitors resemble the substrate and compete for the active site of the enzyme, preventing substrate binding. This characteristic distinguishes them from other types of inhibitors.

How can the effect of a competitive inhibitor be overcome?

• By decreasing substrate concentration

• By increasing substrate concentration

• By adding more inhibitors

• By changing the enzyme's pH

Answer explanation

The effect of a competitive inhibitor can be overcome by increasing substrate concentration. This is because higher substrate levels can outcompete the inhibitor for the active site of the enzyme.

Where do non-competitive inhibitors bind on an enzyme?

• At the active site

• At an alternative site

• At the substrate

• At the enzyme's surface

Answer explanation

Non-competitive inhibitors bind at an alternative site on the enzyme, not at the active site. This binding changes the enzyme's shape, reducing its activity regardless of substrate concentration.

What is the effect of non-competitive inhibitors on Vmax?

• Increases Vmax

• Decreases Vmax

• Has no effect on Vmax

• Stabilizes Vmax

Answer explanation

Non-competitive inhibitors bind to an enzyme regardless of substrate presence, reducing the overall number of active enzyme molecules. This leads to a decrease in Vmax, as the maximum reaction rate cannot be achieved.

How do non-competitive inhibitors affect enzyme conformation?

• They enhance enzyme conformation

• They change enzyme conformation

• They stabilize enzyme conformation

• They have no effect on enzyme conformation

Answer explanation

Non-competitive inhibitors bind to an enzyme at a site other than the active site, causing a change in enzyme conformation. This alteration affects the enzyme's ability to catalyze reactions, making 'They change enzyme conformation' the correct choice.

What happens to enzyme activity when non-competitive inhibitors are present?

• It increases regardless of substrate concentration

• It decreases regardless of substrate concentration

• It remains unchanged

• It becomes more efficient

Answer explanation

Non-competitive inhibitors bind to an enzyme regardless of substrate concentration, reducing the overall number of active sites available. This leads to a decrease in enzyme activity, making the correct choice 'It decreases regardless of substrate concentration'.

What is the overall effect of high pH on enzyme function?

• Enhances enzyme function

• Negatively impacts enzyme function

• Has no effect on enzyme function

• Stabilizes enzyme function

Answer explanation

High pH can denature enzymes, altering their structure and reducing their activity. This negatively impacts enzyme function, making it less effective in catalyzing reactions.

How do competitive inhibitors affect enzymes?

• They alter the enzyme's conformation

• They compete for the active site

• They increase enzyme production

• They stabilize the enzyme

Answer explanation

Competitive inhibitors affect enzymes by competing for the active site, preventing substrate binding. This reduces the rate of reaction without altering the enzyme's conformation or increasing its production.